The present invention relates generally to institutional cooking appliances and cooking food in such appliances. More particularly, the present invention relates to an improved cooking appliance utilizing a computerized controller and an improved method for cooking food utilizing said improved cooking appliance so as to obtain a consistent cooked food product.
Restaurants strive to meet customer""s needs and expectations at every opportunity. Such needs and expectations, however, are oftentimes inconsistent. For example, customers typically seek fast service, even to the extent of utilizing xe2x80x9cdrive-throughxe2x80x9d or xe2x80x9cfast foodxe2x80x9d restaurants. In some restaurants, the customer may not need to leave his or her automobile to hurriedly place an order, to be served or to pay for the food. That same customer, however, will also want food that is fresh and well prepared. That same customer does not want an overcooked or overheated food item.
The restaurant also has certain needs and expectations. The restaurant will expect to prepare a significant volume of properly cooked food. The restaurant will typically purchase or lease specialized industrial appliances to prepare food on a large scale. That cost is significant. The restaurant will also seek to consistently serve quality, well-cooked food. Consistent food preparation is a constant challenge for the establishment and its employees. The restaurant further expects to be profitable. The restaurant will, therefore, seek to minimize both fixed and variable cost, including labor costs. One way of reducing labor costs is to require a single employee to perform multiple tasks. For example, the same employee that operates a cooking appliance may also be required to take a customer""s order, package cooked (or other) food, deliver that food to the customer or process the financial transaction. As the food service employee is asked to provide such a wide range of tasks, it can be difficult to insure food quality through proper operation of the cooking appliances.
Restaurants often use industrial cooking appliances to prepare large quantities of food. One such industrial appliance is a deep fat fryer, including those manufactured by the Henny Penny Corporation of Eaton, Ohio. Prior art electric heating systems are known to provide a plurality of coils that surround the cooking well so that heat is transferred from the coils (sometimes referred to as the heating elements) to the oil in the cooking well. Prior art gas heating systems are known to provide tubes or pathways of heated air that surround the cooking well to impart heat to the oil.
Conventional use of such a fryer entails several steps. A predetermined amount of shortening is placed in the fryer""s cooking well. In its unheated state, certain types of shortening consist of a solid with a paste-like consistency and appearance. The fryer""s heating element is operated to melt the shortening to a liquid oil, and then to heat the oil to a desired cooking temperature. Other oils are conventionally provided in liquid form, even at ambient temperatures. The fryer is provided with an oil temperature sensor. Once the sensor indicates that a desired cooking temperature has been reached, a food product to be cooked is loaded into a carrier. The carrier is placed over and then mechanically xe2x80x9cdroppedxe2x80x9d or eased into the hot cooking oil. Alternatively, the food product may be placed directly into the cooking well without use of a carrier or the like. As a result of this drop, it is known that the cooking oil will encounter xe2x80x9cthermal shock,xe2x80x9d a lowering of the cooking oil temperature. It is known in the art to anticipate the drop and compensate for the anticipated drop by activating the heating system as soon as the cook cycle is initiated, regardless of whether the control system senses a drop in the oil temperature sufficient to cause the heating control to switch on. This practice is intended to remove the inherent delay the physical temperature sensing device requires to register the drop in oil temperature and to cause heating of the oil to begin.
It is further known in the art to provide the fryer a timer that should be activated consistently relative to the drop of uncooked food product into the cooking oil. The timer ideally operates to track the cook time and, once that time has expired, cooperates with an alarm to alert the operator of the conclusion of a cooking cycle.
The food product is typically cooked in the oil at a programmed or xe2x80x9csetxe2x80x9d temperature for a programmed or xe2x80x9csetxe2x80x9d period of time, regardless of batch size or the starting temperature of the food product or the starting temperature of the cooking oil. In many instances, these settings are fixed, making no compensation for temperature changes in the oil due to differing product temperatures or batch sizes. (Differing batch sizes may arise due to differing numbers of items being cooked or differently sized items, such as differently sized chicken breasts.) In more sophisticated appliances, often referred to in the art as xe2x80x9ccompensating controls,xe2x80x9d adjustments in cook time are made according to a linear scheme to compensate for oil temperature variations. Such schemes, in general, provide that if the sensed oil temperature drops xe2x80x9cxxe2x80x9d degrees, the cook time is augmented xe2x80x9cyxe2x80x9d percent; if the sensed oil temperature drops by xe2x80x9c2xxe2x80x9d degrees, the cook time is augmented xe2x80x9c2yxe2x80x9d percent; etc.
Another prior art appliance strategy is to manage the cooking oil temperature according to a predetermined temperature curve. The basic intent of this strategy is to expose the product being cooked to a similar environment for each cook cycle. An unfortunate by-product of this approach is that it tends to cook many batches slower than necessary because the predetermined temperature curve is typical based upon cooking a full or complete load. Accordingly, less than a full load is subjected to a lower cook cycle than is actually needed. The prior art has failed to recognize that the cook cycle and its associated attributes do not necessarily follow a linear model or scheme.
At the conclusion of that xe2x80x9csetxe2x80x9d time, an alarm sounds to alert the operator. The fryer is opened and the carrier is raised from the cooking well. The food product may be suspended over the cooking well for a brief period to allow hot oil to drain back into the cooking well. The cooked food product is then removed from the carrier and placed in a warming tray or the like for service to a customer.
Deep fat fryers are widely used to cook various food products, including but not limited to chicken, beef, fish, onions and potato products such as french fries and potato cakes. In each case, it is desirable to produce a consistently and properly cooked product. For example, undercooked chicken or meat may be contaminated by disease such as xe2x80x9ce coli.xe2x80x9d At the same time, overcooked chicken or meat is undesirable to the customer.
The inventor has determined that variations in the cooked product may result from a variety of causes. These causes range from variations in the heating parameters, inherent limitations in prior art fryers, and variable operation of the fryer by an employee who has multiple tasks to perform. Such causes are discussed in greater detail hereinbelow. One limitation of prior art fryers is oil temperature stratification. The inventor has discovered that this condition results in different areas of the cooking well having oil heated to differing temperature. Oil temperature stratification occurs gradually over time due to idling or rapidly after an initial heat-up of the fryer. A simplified diagrammatic example of oil temperature stratification is shown in FIG. 1, which shows a cooking well with 3 levels of stratification. In this example, the temperature sensor is placed near the top of the cooking well. The desired cooking temperature is 325xc2x0 F. and, as shown, the temperature sensor indicates that the cooking oil temperature is 325xc2x0 F. However, due to oil temperature stratification, the oil temperature in the middle strata is only 300xc2x0 F. (for example) and the temperature in the bottom strata is only 275xc2x0 F. (for example). Thus, while the sensed temperature is 325xc2x0 F., the average temperature in the cooking well is 300xc2x0 F. and the temperature of the oil at the bottom of the well is significantly lower than the sensed temperature at the top of the well. Even if the oil in the cooking well was thoroughly stirred, the resultant temperature of the oil immediately after stirring would be approximately 300xc2x0 F., not the desired cooking temperature of 325xc2x0 F. It is to be understood that the foregoing is exemplary. The temperatures selected are for ease of description and demonstration. The problems associated with oil temperature stratification include inadvertently undercooking the food product and failing to account for a stirring of the oil, whether by manually stirring the oil or as a result of agitation due to cooking. Those of ordinary skill will appreciate that this temperature variation can be significant in terms of the cooked product. Photograph A shows chicken products cooked to varying internal temperatures, ranging from 285xc2x0 F. to 345xc2x0 F. in 15xc2x0 F. intervals. As shown, the chicken cooked to 285xc2x0 F. is significantly lighter than the chicken cooked to 315xc2x0 F. Further, the chicken cooked to 345xc2x0 F. is significantly darker than that cooked to 315xc2x0 F.
Those of ordinary skill in the art will also recognize that another primary concern of fryer operation is to maintain a suitable cooking medium. The person of ordinary skill in the art is aware that the cooking process negatively affects the oil over time, and that cooking oil has a finite life. As an example, small pieces of food may be left in the oil. Also, the cooking oil will absorb oils and other materials from the food. It is, therefore, necessary to periodically filter the cooking oil in order to maintain a quality cooking medium.
It is known to provide a deep fat fryer with a filtering mechanism based upon the number of completed cook cycles. See, for example, U.S. Pat. No. 4,913,038, which generally addresses the need to filter the cooking oil. The ""038 patent discloses a computerized control system for use with a deep fat fryer. The ""038 patent recognizes the need to provide consistent cooked food quality through efficient and economical operation of the fryer. The ""038 patent is directed to providing a selectable proportional control factor for controlling the heating element of the fryer. While such prior art methods and devices are extremely helpful in many respects, there is room for improvement. For example, many such prior art systems fail to recognize or compensate for the temperature stratification in the cooking oil due to the filtering process. The filtering process will also affect the temperature of the cooking oil, due to its removal from the heat source and aeration during the filtering and pumping operation. The cooking oil temperature will typically lower the average temperature of oil in the cooking well because the filtering operation mixes-up the oil.
A variety of other causes may produce an undesirable result. For example, once the restaurant has closed for the evening, it is typical to significantly reduce the temperature of the oil in the fryer, or even to turn the fryer off completely. This operation conserves energy and saves on related costs. Of course, this also requires that the fryer be restarted or at least that the shortening be reheated the next day before food products can be cooked in the fryer for sale that day. It is known in the art that the first run of cooked product, after a start-up, is typically of a different, usually of lower quality, as compared to later runs as the shortening reaches an efficient and proper operating temperature and condition. Of course, it is also possible that the first run of the day may often produce products that are of a different quality than later cooked product. The challenge to cook consistently remains. A related concern is that an operator may add new oil (at ambient temperature) to a fryer as necessary which also lowers the temperature of heated oil.
There are yet other factors that may cause differences in the final cooked product. For example, conventional deep fat fryers are constructed to cook a certain amount of product. The traditional amount is often referred to as a xe2x80x9cloadxe2x80x9d. However, while it may be desirable to cook a full load at lunch or dinner times, there are certainly other times when it may be desirable to cook only a partial load. Under such conditions, the standard cook settings of a conventional deep fat fryer may not be appropriate, thus making it necessary for an operator to monitor the partial load and adjust the fryer conditions as necessary.
Yet other factors may affect the final outcome of cooking a full or partial load of product in a deep fat fryer. For example, the heating element may not be providing a consistent heat source. This problem may be reflected in several ways. The input voltage may be below normal, or one of the heating elements may not be functioning properly or perhaps a heating coiled has failed entirely. Heating coils are recognized to have certain life-span and as the coil life approaches failure, it is possible that the coil is not performing adequately. Yet other factors include the size of the load or xe2x80x9cbatchxe2x80x9d being cooked. Poorly cooked product may result from too small of a load, too large of a load or from the temperature of the product immediately prior to being cooked. For example, if the operator inadvertently places frozen un-cooked product into the fryer, but the fryer has been set to cook a thawed xe2x80x9cload,xe2x80x9d the product may not be fully cooked.
Yet another concern discovered by the applicant is that the oil temperature within the cook well is not consistent. Instead, the oil temperature in prior art fryers often tends to stratify, such that the greatest or highest oil temperature is food at the top of the well and the lowest temperature is found at the bottom of the well. As a result, the food product being cooked at the top of the well is being cooked in a hotter oil than that food product at the bottom of the cook well. Thus, even within a single batch, the same product may be cooked with different results due to oil temperature stratification. Such stratification is inherent to the equipment and has gone unaddressed in the prior art.
Yet other cooking concerns include improper filtering of the oil during the many cooking cycles performed during a day and operator error such as improper loading of the chicken (too slow) or improper operation of the fryer (premature starting of the timer, etc.). Yet another concern is the need to recognize and compensate for failures in the fryer""s heating system. A heating coil failure or a xe2x80x9cbrown outxe2x80x9d may alter the temperature stratification typically found in the cooking well. A portion of the cooking oil may be unduly cool for cooking. Alternatively, the operator may notice that the chicken is not cooking completely and attempt to compensate by adjusting the temperature control upward or by extending the cooking time interval. Such operation is not only inefficient, it may also negatively affect the cooked product. Thus there is a need in the art for an improved control system for deep fat fryers that recognizes undue variances in the cooked product and the cooking process that may result from differing batch or piece size, fryer performance and product temperature.
The foregoing problems include, but do not fully recognize, the difficulties experienced by an operator or food establishment employee when using the industrial cooking appliance. Every restaurant, whether classified as a xe2x80x9cfast food,xe2x80x9d diner or formal establishment, experiences times that are very busy and times that are slower. Every restaurant seeks to maximize profit, often by asking an employee to perform multiple tasks or xe2x80x9cto coverxe2x80x9d for an absent employee. This difficult position may result in depriving the employee of sufficient time to perform properly the cooking operation. For example, the employee may be so hurried that he or she may not activate the fryer""s timer at the correct time. Such problems may be a result of high demand. For example, a food service person who has many customers impatiently waiting may ask or require that oversized loads or inappropriately frozen food be processed in the fryer or oven. If such an occurrence is frequent, management would need to be aware of such information so as to determine whether to purchase another fryer (or oven) or hire additional people or otherwise manage the business demand.
Several factors can, therefore, significantly affect the preparation of foods in a fryer. These factors include: (1) variations in the cook time (such as a variance in the start time of the timer due to operator distraction); (2) oil temperature stratification resulting from filtering cooking oil in the cook well; (3) oil stratification resulting from idling of the fryer during non-cooking periods; (4) variations in the uncooked product including product initial temperatures, batch size and unit size; (5) variation due to the condition or life of the cooking oil; and (6) variations in fryer performance.
The present invention addresses these problems of prior art fryers and method of use by providing an improved cooking appliance and method of cooking food products therein. More specifically, the present invention provides a computerized controller that recognizes the problems associated with prior art fryers and provides means for correcting such problems so as to consistently obtain the desired cooked food product.
Generally described, an apparatus according to the present invention includes a computerized controller and a cooking appliance, the appliance including a cooking well for operative retention of a cooking material, a heating element for heating the cooking material and a temperature sensor, and means for adjusting the cook time and temperature in response to certain sensed or programmed data so as to produce a consistent, well-cooked product. A method of cooking in accordance with the present invention includes cooking a food product in accordance with one or more diagnostics or cooking compensations that yield a consistent, well-cooked product. Yet further, the present invention includes a food item cooked in accordance with the invented method as, for example, by a cooking appliance made in accordance with the present invention.
Thus, a preferred embodiment of the present invention collects and maintains four (4) types of information: (1) cook data, which includes information relating to the immediately preceding cooking cycle; (2) day data, which includes information relating to the current day; (3) oil data, which includes information relating to the current oil batch; and (4) previous oil data, which includes information relating to the previous oil batch. The invention includes use of a computer. Programming logic discerns the beginning of a new day and when the oil has been changed. The present invention contemplates that such information may be discerned without need or use of a clock device. Programming logic may also be used to determine when information is converted or transferred, such as from xe2x80x9ccook dataxe2x80x9d to xe2x80x9cday data.xe2x80x9d
The present invention employs a set of diagnostics to effect certain working compensations in order to produce a consistently cooked, high quality product. A first diagnostic is to determine if heating rates are acceptable during a start-up period and after a filtering operation. To effect this diagnostic, an appropriate time value or range is determined empirically to represent acceptable heating between two temperatures, such as 270xc2x0 F. and 310xc2x0 F., and programmed into the computer. The actual time for the improved cooking appliance to progress from a first temperature to a second temperature, and/or the maximum rate of temperature rise between these two points, is monitored and captured. The captured actual time is then compared to the programmed value to determine if heating time is within the acceptable value or range. If heating is slow, an alarm may be actuated. The slow heat occurrence is added to the xe2x80x9ccook data.xe2x80x9d
A second diagnostic is to determine if the power supply voltage is sufficient during fryer operation. The actual power supply voltage is monitored and averaged over a moving or sliding averaged time period (i.e., 10 seconds). If the actual power voltage calculated average drops below a predetermined acceptable value that is programmed into the computer, an alarm is activated. This occurrence is added to and stored in the xe2x80x9cday data.xe2x80x9d
A third diagnostic is to determine if an actual cook cycle time is within acceptable limits. To conduct this diagnostic, each menu item is empirically given a range of acceptable cook times. The actual time required to complete a cook cycle for a given menu item is compared to a predetermined xe2x80x9cslow cook timexe2x80x9d programmed into the computer. If the actual time exceeds the slow cook time, an alarm may be activated. The slow cook time occurrence is added to the cook data.
A fourth diagnostic is to determine if an actual cook cycle time exceeded a maximum limit for cooking acceptable product. To conduct this diagnostic, each menu item is empirically assigned a programmable discord product value.xe2x80x9d The actual cook time is compared to the appropriate discard product value. If the actual cook time exceeds the discard product value, an alarm may be activated. A display is preferably provided informing the operator to discard the product. This discard product occurrence is added to the cook data.
A fifth diagnostic is to determine if the oil in the cooking well has been stirred. To conduct this diagnostic, a programmable oil temperature value is determined. If a negative oil temperature gradient is sensed and that gradient exceeds the programmed value, and a menu or operation button is not depressed (as for example, to initiate a cook cycle), the invention infers or thus xe2x80x9cdetectsxe2x80x9d that an oil stir has occurred.
Utilizing one or more of such diagnostics, the preferred embodiment of the present invention is able to effect a variety of cooking compensations. A first cooking compensation is for xe2x80x9cnew oilxe2x80x9d To compensate for the effect of replacing unsuitable or xe2x80x9cold oilxe2x80x9d in the cooking well, sensed oil temperature is adjusted by an amount prorated over a select number of cooking cycles. The prorated adjustment is added to a reference temperature to determine an appropriate cooking time expansion or contraction period for use in the cook time compensation described hereinbelow. This xe2x80x98new oilxe2x80x9d compensation may have multiple levels. For example, the compensation may include an oil temperature gradient from 10xc2x0 F. to 3xc2x0 F. over 30 cook cycles; a decreasing oil temperature gradient from 3xc2x0 F. to 2xc2x0 F. over the next 70 cook cycles; and a decreasing oil temperature gradient from 2xc2x0 F. to 0xc2x0 F. over the next 900 cook cycles.
A second compensation is for the effects of oil temperature stratification after filtering the oil or after start-up. This compensation specifies that the sensed oil temperature be increased a predetermined appropriate amount over and above the desired cooking temperature. This compensation further provides that this offset is discontinued with the start of a cook cycle or the detection of a stir.
A third compensation is for the effects of oil temperature stratification due to oil idling. To effect this compensation, a prorated increase in temperature is made to the desired cooking temperature over a predetermined time period. This prorated increase is eliminated (reset to xe2x80x9c0xc2x0 F.xe2x80x9d) when a stir is detected or upon the start of a cook cycle.
A fourth compensation is for a variation in operating procedure. This compensation bases the start of a cook cycle on a sensed oil temperature drop. Thus, rather than utilizing prior art methods relying on an operator""s initiation of the cook cycle by pressing a button or the like, this compensation relies on a change in the temperature of the oil within a predetermined time range enveloping the cook cycle activation (i.e., pressing the xe2x80x9cstartxe2x80x9d button).
A fifth compensation is used to compress or augment the time variable during a cook cycle to counteract sensed temperature differences as opposed to a temperature reference point. This compensation utilizes a unit of time and, for each unit compares the sensed actual oil temperature with a reference temperature. Based on that comparison, the preferred embodiment utilizes a non-linear compensation algorithm to calculate a compensation value by a defined or programmable exponential equation. According to this value, the invention contemplates that the cook time element will be augmented or compressed accordingly.
Thus, it is an object of the present invention to provide an improved cooking appliance and method for use thereof.
It is a further object of the present invention to provide an improved cooking appliance and method for use that employs a set of diagnostics to effect working compensations in the cooking operation so as to obtain a consistent and well-prepared food product.
It is a further object of the present invention to provide an improved cooking appliance and method of use that addresses several factors that can significantly affect the consistency of a fried or cooked food product, including variances due to operator error or distraction.
It is a further object of the present invention to provide an improved cooking appliance and method of use that addresses variances in cooked foods due to limitations in prior art appliances such as cooking oil stratification.
It is a further object of the present invention to provide an improved cooking appliance and method of use that addresses variances in cooked foods due to variable factors such as batch size, fryer performance, product temperature and oil life.
It is a further object of the present invention to provide an improved cooking appliance and method of use that addresses variances in cooked product due to condition of the cooking oil.
It is a further object of the present invention to provide an improved cooking appliance and method of use that addresses maintenance of the appliance, including the difficulty of recognizing and trouble-shooting fryer performance and operation.
It is a further object of the present invention to provide an improved cooking appliance and method of use that compensates for the effects of new oil placed in a cooking appliance.
It is a further object of the present invention to provide an improved cooking appliance and method of use that compensates for the effects of oil temperature stratification.
It is a further object of the present invention to provide an improved cooking appliance and method of use that compensates for variations in or procedures employed to operate the appliance.
It is a still further object of the present invention to provide an improved cooking appliance and method of use that adopts and utilizes a non-linear, exponential compensation algorithm that augments or compresses cook time as necessary or appropriate.
It is a still further object of the present invention to provide an improved cooking appliance and method of use that adapts and utilizes a non-linear, exponential compensation algorithm that is timeable to the particular food item being cooked.
It is a still further object of the present invention to provide an improved cooking appliance and method of use that may be retrofit to existing prior art appliances.
It is a still further object of the present invention to provide a cooked food product that has been cooked in accordance with a method of the present invention.
It is a still further object of the present invention to provide an improved cooking appliance and method of use that utilizes diagnostic information to enhance performance of both the appliance and the operator through implementation of working compensations to produce a consistent, higher-quality cooked food product.